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route and climber ratings for rock climbing
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climbing_ratings
.gitignore
00-data_prep_functions.R
01-data_prep.R
02-run_estimation.py
03-post_estimation.R
LICENSE.txt
README.md
setup.py

README.md

climbing_ratings

climbing_ratings estimates ratings for the sport of rock climbing. The ratings can be used to predict route difficulty and climber performance on a particular route. It is written by Dean Scarff.

The algorithms are based on the "WHR" paper:

Rémi Coulom, "Whole-History Rating: A Bayesian Rating System for Players of Time-Varying Strength", https://www.remi-coulom.fr/WHR/WHR.pdf.

Equivalences to the WHR model are:

  • Climbers are players.
  • Ascents are games.
  • A clean ascent is a "win" for the climber.

Notable differences are:

  • Routes are like players except their rating does not change with time.
  • The gamma distribution is used for the prior distribution of route and initial climber ratings.
  • A "page" is the model of a climber in a particular time interval (like a page in a climber's logbook). This is equivalent to a player on a particular day in WHR, except that the time may be quantized with lower resolution (e.g. a week).

Contents and Usage

Python library

The estimation algorithms are implemented in Python and Cython, in the climbing_ratings package. Some effort has been taken to optimize parts of the code for speed, namely by leveraging numpy for vectorized operations and using Cython to reduce Python overheads and allow C compilers to generate vectorized CPU instructions.

The package can be built using:

python3 setup.py build

Unit tests can be run using:

python3 setup.py test

Estimation script

The Python script 02-run_estimation.py reads in set of CSV files and writes out the estimated ratings for pages and routes as CSV files. To read and write CSV files from the data/ directory, it can be run like:

python3 02-run_estimation.py data

It will typically less than a second per 10,000 ascents (measured on an Intel Core i5-8210Y).

R scripts

A collection of R scripts are used for data preparation and results analysis. They can be sourced into an R session. The scripts use several libraries from the "tidyverse" collection, which can be installed from R:

install.packages("tidyverse")

Together, 00-data_prep_functions.R and 01-data_prep.R create appropriate input CSV files for 02-run_estimation.py.

The 03-post_estimation.R script merges the estimation results with the data frames created by 01-data_prep.R, and produces some plots that can be used to analyze the model fit.

With the file data/raw_ascents.csv already present, the entire pipeline can be run from R:

data_dir <- "data"
source("00-data_prep_functions.R")
source("01-data_prep.R")
system2("./02-run_estimation.py", data_dir)
source("03-post_estimation.R")

The raw_ascents.csv file can be regenerated from a directory containing CSV logbook exports from theCrag. Having sourced 00-data_prep_functions.R, and with the logbooks in the directory "logbooks":

write.csv(
  ReadLogbooks("logbooks"),
  "data/raw_ascents.csv",
  quote = FALSE,
  row.names = FALSE
)

Interpreting ratings

Ratings come in two flavours; the gamma rating and the "natural" rating r; they are related by gamma = exp(r).

Suppose a climber whose current rating is gamma_i attempts to climb a route with rating gamma_j. The model predicts the probability of the ascent being clean as:

    P(clean) = gamma_i / (gamma_i + gamma_j)
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